1. Field of the Invention
The present invention relates to bipyridine-based compounds and organic light emitting diodes (OLED) employing organic layers including the same. More particularly, the invention is directed to bipyridine-based compounds suitable for electron transport layers of OLEDs and to OLEDs employing organic layers including the bipyridine-based compounds.
2. Description of the Related Art
Organic light emitting diodes (OLEDs) are self-emitting devices that realize multiple colors and have wide viewing angles, excellent contrast and quick response. A typical OLED structure includes an anode, a hole transport layer (HTL), an emitting layer (EML), an electron transport layer (ETL) and a cathode sequentially stacked on a substrate. The HTL, EML and ETL are thin films formed of organic compounds. An OLED with such a structure operates by applying a voltage to the anode and cathode, which causes holes injected from the anode to move to the EML via the HTL, and electrons injected from the cathode to move to the EML via the ETL. The holes and electrons recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, a fluorescent material in the EML emits light. The material used to form the ETL may be a heteroaromatic compound such as an oxadiazole, a thiadiazole, or the like. However, conventional OLEDs have insufficient driving voltage, current density, efficiency and lifetime characteristics.